Today, we ask why three roads should run parallel
to each other. The University of Houston's College
of Engineering presents this series about the
machines that make our civilization run, and the
people whose ingenuity created them.
In 1854 the Irish physicist
John Tyndall lectured on science education in
London. Science he said, begins with a question. To
answer a question about nature, we must first
observe. We must take in sense data -- heat, light,
sound. But, he continues,
we observe the fact, but are not satisfied with
observation: the fact must be accounted for ... we
transfer [facts] to the domain of thought: look at
them, compare them, [bring] them ever clearer
before the mental eye. [And finally we] alight upon
the cause which unites them.
Tyndall came back to that elemental
theme again and again. We must move back and forth
between an observed world and an invented world. It
is never enough to observe. It is never enough to
theorize. We must do both, or we accomplish nothing.
Then, 22 years later, Tyndall gave another lecture.
This time he talked about the mysterious parallel
roads of Glen Roy.
Glen Roy is the valley of the River Roy in
Scotland. High on either side, three parallel roads
wind along the canyon wall -- only a stone's throw
Tyndall had found a question, all right. Those
remote improbable roads were there long before any
account of them. But, for the last hundred years,
people had been asking why three roads should be
made parallel to one another. He says,
[We need] two distinct mental processes [to
treat] such a question. [First,] faithful
observation of the data; [second,] that higher
mental process in which the constructive
imagination comes into play, connecting separate
facts with their common cause, and weaving them
into an organic whole.
Tyndall asks us to begin with detached
observation. Then we undertake the very personal
process of inventing a theory.
Scottish country folk had done that. They explained
those crazy roads by saying their ancestors had
made them as open areas to tempt game out of the
brush and into a vulnerable position.
Then the scientists came. They said, Wait a minute!
Those aren't roads at all. They're terraces formed
by water levels in the valley. That's why their
elevation doesn't vary. But how did the valley fill
with water for long periods and then empty out?
They finally saw how subsequent glaciers had dammed
the outlet of the valley. By the time they had it
right, the great minds of the age had wrestled with
those mad roads that weren't roads at all --
Charles Darwin, Louis Agassiz, and Tyndall, too.
Tyndall didn't really care about the answer -- even
though he'd helped to find it. He wanted us to know
the process that begins with a small question about
three crazy roads and ends with a new understanding
of geology. What held Tyndall's heart was the joy
of marrying the mind to external data. That
essential act of science is laid bare in our
response to a question about eerie roads that
weren't at all what they seemed to be.
I'm John Lienhard, at the University of Houston,
where we're interested in the way inventive minds
Tyndall, J., Fragments of Science. Vol.
I, 6th ed., New York: D. Appleton and Co., 1899,
Chapter VIII, The Parallel Roads of Glen Roy.
Tyndall's first written reference to the parallel
roads of Glen Roy was Pennant, T, A Tour in
Scotland. Vol. iii, 1776, p. 394.
For more on Tyndall see Episodes 192, 531,
624, 642, and 1067. The Tyndall quotations have
been edited down for use on the radio. See the
source for complete quotations. Much additional
material on Tyndall and on the observations of many
Scottish naturalists is available in Special
Collections, UH Library.
Image courtesy of Special
Collections, UH Library
The parallel roads of Glen Roy (from Fragments
of Science, 1899)
Image courtesy of Special Collections, UH Library
John Tyndall, from the frontispiece of his book,
Forms of Water in Clouds
and Rivers, Ice and Glaciers, 1874
The Engines of Our Ingenuity is
Copyright © 1988-2004 by John H.